An excellent AP article by Todd Lewan discusses how RFID technology can be used to spam the living lights out of you, as well as how to track you and in general violate your privacy.
While I believe RFID technology is extremely useful, it must be regulated in order to avoid abuses. We cannot simply take the word of corporations and/or government that they’ll take good care of our personal data. In fact, the article shows that corporations are not concerned with our privacy, and primarily worry about it when confronted with consumer backlash and the prospect of regulation.
Without regulation things will escalate out of control, and we’ll all feel like the tourists in places like Cancun. Cancun is a beautiful place, with a fantastic waterfront, ancient ruins nearby, and given a chance I will go there again. However, tourists are constantly live-spammed: from the moment you leave the arrival gate at the airport people want to sell you phone cards and blankets, taxis honk to offer a ride, hotel representatives intercept you on the street and offer drinks and try to make you switch accommodations mid-vacation, etc. The pressure is constant. You quickly adapt and start ignoring the offers, but they take some of your freedom away – e.g. you can’t just let your gaze wander for fear of making eye contact with a street vendor. In a world where RFID is abused for commercial gain, and other purposes, we’ll also have to develop evasive maneuvers and this too will take some of our freedom away.